Doing any kind of home improvement work yourself brings a lot of personal satisfaction. In addition, you can save yourself thousands of dollars in labor costs. Laying cobblestones is not a tricky process, but making sure the cuts are straight can be. You will need the right tools and a few practice cobblestones at first. Depending on your project, you might need really clean cuts or you might need rugged looking cuts. This will determine what kind of tool you use.
Buy a few extra cobblestones for practice. When starting out you will have a few stones that either break in half or don't work right.
Acquire the tool you will be using to cut the cobblestones with. If the cobblestones are close together without much spacing, you might want to rent a diamond saw from your local home improvement store. If you want more rugged cuts or straightness doesn't matter as much, buy either a masonry cutting wheel or a block splitter.
Practice cutting a few stones first before you are ready for your first cut. Use your chalk straight edge to mark them and see how close you can come to making them perfect.
Put the stone on a soft surface like the sand if you are using a stone cutter. Make sure the cutter lines up with your mark and hit it hard with a mallet or sledge hammer. The block should slit right on the line. For a diamond saw, simply cut the cobblestone along the line like you would a piece of wood.
Start making similar cuts when you are ready. The key to speed is trying to figure out if you have some stones that need to be split at the same length and doing all of them at once. Remember that it is not good to cut big because, unlike wood, you cannot recut a small piece off unless you have a diamond saw.